The Club for Growth, the powerful pro-free-market group, endorsed three candidates for Congress today.

The club's PAC gave its nod to Keith Rothfus, the GOP nominee in Pennsylvania's 12th district against Rep. Mark Critz (D); Thomas Massie, a tea-party-affiliated candidate in the crowded GOP primary in Kentucky's open 4th district; and state Sen. Ron Gould, taking on Rep. Paul Gosar and Pinal County Sheriff Paul Babeu in a competitive GOP primary in Arizona's 4th district.

The endorsement of Rothfus is not a surprise. The club's PAC backed him in his 2010 race against Rep. Jason Altmire (D). But its backing of Massie has the potential the change the dynamic of a competitive Republican primary to replace retiring Rep. Geoff Davis (R).

Massie, the Lewis County Judge-Executive, faces Boone County Judge-Executive Gary Moore and state Rep. Alecia Webb-Edgington, among others. Webb-Edgington has the backing of the GOP establishment in the race, while Sen. Rand Paul (R-Ky.) helped recruit Massie to run.

“Tom Massie is the best choice for Kentucky Republicans looking to send a message to Washington D.C.,” Club for Growth President Chris Chocola said in a statement. “Like Senator Rand Paul, Tom will fight the big-spending Washington establishment, repeal ObamaCare, and stop the liberals who are bankrupting America. The Club’s PAC strongly supports Tom Massie for Congress.”

The club's endorsement also the potential to stir up the race in Arizona, which already was rocked by revelations that Babeu is gay.

“Ron Gould is a taxpayer superhero and will be a champion for pro-growth policies in Congress,” Chocola said.